County using high-tech sensors to track Pinellas Trail traffic

SEMINOLE — At 47 miles long, it’s not easy to tell how many walkers, cyclists and roller skaters are using the Fred Marquis Pinellas Trail.

County staff used to stand for an hour with a clipboard and clicker and count manually.

Now, the process is going high-tech.

Infrared and electromagnetic sensors have been installed at five locations along the length of the recreational trail. The sensors, which can tell the difference between a cyclist and a pedestrian, transmit a count of traffic to a central computer every 24 hours. The equipment, which cost a total of $24,600, was paid for by a grant from the U.S. Department of Health and Human Services.

The operation is more than an academic exercise: Traffic counts could help the county obtain transportation grants, plan future maintenance and identify where the trail could be expanded.

“Funding is always tied to numbers,” said Nancy Brown, a coordinator for the county’s Parks and Conservation Resources department. “If we can show how many people are using the trail, we have a better chance.”

Sensors have been permanently installed at locations in south, central and north Pinellas. Two infrared sensors are temporarily mounted on posts on the trail and can be relocated as needed.

The infrared sensors register body heat from pedestrians as they walk past.

The electromagnetic sensors are made up of eight loops of wire buried in the tarmac that detect the passing of bicycle wheels,

“I’ve never seen them miss a person, so that’s exciting,” Brown said. “The detection is really accurate.”

Bicycle-friendly cities such as Portland, Ore., already use a similar system.

County officials spent several weeks testing the sensors. They have been recording data from all five sensors since Aug. 16.

Using manual counts, officials estimated that roughly 355,000 people used the trail in the 2011-12 fiscal year.

So far, daily counts from the sensors show traffic on different trail sections runs between 100 and 1,000 trips.

“We had no way of being able to calculate that data before,” Brown said.